The enduring image of the Eddie O'Sullivan era with Ireland is not a celebration shot from one of three triple crowns, the first delivered after a famine of 19 years, but of the coach backed into a corner with a phalanx of microphones stuck in his face. It was Paris in 2007: Ireland's World Cup had ended as it had started, in disaster, and O'Sullivan was getting it from all angles.

The experience scarred him. For an age afterwards all anybody wanted to talk about was how it had all gone wrong, whereas on the road to that point so much had gone right – and at the time he felt hard done by.

"I had six and a half years at the helm and most of it was enjoyable but it's like most coaching jobs – the end of it can get pretty ugly, starting for me with the World Cup and then the Six Nations that came after it," he says. "It was a pretty tough place to be at the end so there's a sense of relief at not being there and not in the grinder any more. I'm in a place now where there are different optics on the whole thing."

That place is with the US Eagles. It took a long time for O'Sullivan to hitch up with another outfit and as soon as it turned out to be an international side then you knew somehow that they would end up in Ireland's pool at this World Cup. The difference between O'Sullivan's previous and current jobs could hardly be more pronounced.

His time with Ireland started as assistant to Warren Gatland, just after another World Cup disaster – losing to Argentina in Lens in 1999 – as the IRFU were coming round to the notion of spending money to achieve success. O'Sullivan did his bit to cement that policy of sustained investment in the national side, so that by the time he left his Ireland squad wanted for nothing – though his success in so doing added to the criticism that rained down on him at the end.

Life with the Eagles is a different story. They fly so low that they come in well under the financial radar. For example they managed a three-day camp in Santa Barbara before they came to New Zealand only because their assistant manager had a connection with the university there and got it at rock-bottom prices. The players stayed in dorms and ate in the college canteen. Meanwhile Ireland were in the lap of luxury in their country club hotel in Kildare, with everything on hand.

"People don't realise the sacrifices these players make to play for the Eagles and that's part of the attraction, because you're dealing with guys who are so committed to the cause," O'Sullivan says. "It means that any time we do get together is really useful, so we're a lot further down the track from the Churchill Cup in June. We've had three games in August with the whole squad and that three-day camp in California before we left for New Zealand. The time together has been invaluable in terms of getting organised."

The odds are stacked against him, however. In the circumstances his inside knowledge of more than half the Ireland side who start on Sunday does not count for much. More useful is the fact that he is the most experienced coach in the tournament. Including his role as fitness adviser to Ireland in 1991, this is O'Sullivan's fifth World Cup during which time he has learned the following.

"The key criteria which are within your control are to get as organised as possible before the tournament begins; keep players working hard at training but keep sessions short and sharp – don't leave your best rugby moments on the training field – and treat every game differently, ie your gameplan and mental approach have to be specific to the opposition. As for the things you can't control, hope to avoid injuries to key players and benefit from a bit of luck at key moments.

"For us now obviously the Russia game is a target but I'd like in the three tier one games for us to give a good account of ourselves. And I have to keep in mind giving game time to those fellas who need a chance to play, to move them around and give them a shot, even against teams like Australia or Italy."

He has kept close tabs on Ireland since he left and their awful form of last month was something he could identify with and understand. It was a bit of a throwback though to be fronting a press conference on Friday, shades of his final days in the Ireland job.

"It was very strange facing the Irish media after three and a half years out of the hot seat. There's been a lot written about myself and Declan [Kidney, his successor as Ireland coach] and it's been a bit tedious, to be honest. I wonder what purpose it's serving for anybody. Declan doesn't need to prove anything at this stage as a coach and I'd like to feel that the same would apply to me, even if it's to a lesser degree than Declan.

"I've seen the reaction to this year's warm-up games for Ireland and it's exactly like it was in 2007. It heaps extra pressure on the team before there is a ball kicked in anger. Warm-up games are treated like Six Nations games by the media when they are nothing like Six Nations games and serve a completely different purpose.

"Warm-up games are used to select a World Cup squad, to look at different selection combinations and get players match fit as it's their first games of the season while at the same time keeping your tactical powder dry for the main event. None of that is conducive to playing excellent rugby and winning at all costs. So to judge the team on those performances is premature but it does increase the pressure unnecessarily on the players and staff. So I know how Declan feels."

Yes, but it is not his problem. Rather that comprises getting the Eagles up to a level they have never reached before. O'Sullivan is acutely aware of the emotional baggage attaching to 9/11 – the 10th anniversary of which coincides with their match against Ireland – and the need to lighten that load. The Eagles are a passionate bunch at the best of times but the coach will not be looking to add to that.

And he will not be making any excuses about how his Irish experience ended. Perhaps Warren Gatland's inability to park the Ireland job, from which he was dumped to allow O'Sullivan into the driver's seat, has helped him put it into perspective.

"It's like anything that you can't change: you move on," he says.

"And for me I'm delighted to be back at a World Cup again. And it's nice to be back without the same level of pressure and the same expectation around the team. I'm going to enjoy this."